LT3518 Datasheet, PDF (1/20 Pages) Linear Technology – Full-Featured LED Driver with 2.3A Switch Current

LT3518
Full-Featured LED Driver
with 2.3A Switch Current
FEATURES
DESCRIPTION
n _{3000:1 True Color PWM™ Dimming Ratio}
n _{2.3A, 45V Internal Switch}
n _{100mV High Side Current Sense}
n _{Open LED Protection}
n _{Adjustable Frequency: 250kHz to 2.5MHz}
n _{Wide Input Voltage Range:}
Operation from 3V to 30V
Transient Protection to 40V
n _{Operates in Boost, Buck Mode and Buck-Boost Mode}
n _{Gate Driver for PMOS LED Disconnect*}
n _{Constant-Current and Constant-Voltage Regulation}
n _{CTRL Pin Provides 10:1 Analog Dimming}
n _{Low Shutdown Current: <1μA}
n _{Available in (4mm × 4mm) 16-Lead QFN and 16-Pin}
TSSOP Packages
APPLICATIONS
n _{Display Backlighting}
n _{Automotive and Avionic Lighting}
n _Illumination
n _Scanners
The LT^®3518 is a current mode DC/DC converter with an
internal 2.3A, 45V switch specifically designed to drive
LEDs. The LT3518 operates as a LED driver in boost, buck
mode and buck-boost mode. It combines a traditional
voltage loop and a unique current loop to operate as a
constant-current source or constant-voltage source. Pro-
grammable switching frequency allows optimization of the
external components for efficiency or component size. The
switching frequency of the LT3518 can be synchronized
to an external clock signal. The LED current is externally
programmable with a 100mV sense resistor. The external
PWM input provides 3000:1 LED dimming. The CTRL pin
provides further 10:1 dimming ratio.
The LT3518 is available in the tiny footprint 16-Lead QFN
(4mm × 4mm) and the 16-Pin TSSOP package. The LT3518
provides a complete solution for both constant-voltage
and constant-current applications.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. True Color
PWM is a trademark of Linear Technology Corporation. Patent Pending. All other trademarks are
the property of their respective owners. *Patents Pending.
TYPICAL APPLICATION
1.5A Buck Mode LED Driver
PV_IN
24V
V_IN
3.3V
2.2μF
V_REF
PWM
68mΩ M1
2.2μF
ISP
V_IN
SHDN
ISN TG
SW
LT3518
CTRL
FB
PWM
SS
SYNC
R_T
TGEN V_REF V_C GND
0.1μF
1.5A
16.9k
1MHz
10μF
15μH
0.1μF
3518 TA01a
Efficiency
100
CTRL = V_REF
90
80
70
60
50
40
0
20
40
60
80 100
PWM DUTY CYCLE (%)
3518 TA01b
3518fb
1